Dear all,

on behalf of Matthieu Authier and co-authors, I am pleased to announce the 
publication of our recent article on estimating and detecting trends in 
cetacean abundance.


Happy reading!


Authier M, Galatius A, Gilles A, Spitz J. 2020. Of power and despair in 
cetacean conservation: estimation and detection of trend in abundance with 
noisy and short time-series. PeerJ 8:e9436 DOI 10.7717/peerj.9436


open access

https://peerj.com/articles/9436/


Abstract:
Many conservation instruments rely on detecting and estimating a population 
decline in a target species to take action. Trend estimation is difficult 
because of small sample size and relatively large uncertainty in 
abundance/density estimates of many wild populations of animals. Focusing on 
cetaceans, we performed a prospective analysis to estimate power, type-I, sign 
(type-S) and magnitude (type-M) error rates of detecting a decline in short 
time-series of abundance estimates with different signal-to-noise ratio. We 
contrasted results from both unregularized (classical) and regularized 
approaches. The latter allows to incorporate prior information when estimating 
a trend. Power to detect a statistically significant estimates was in general 
lower than 80%, except for large declines. The unregularized approach (status 
quo) had inflated type-I error rates and gave biased (either over- or under-) 
estimates of a trend. The regularized approach with a weakly-informative prior 
offered the best trade-off in terms of bias, statistical power, type-I, type-S 
and type-M error rates and confidence interval coverage. To facilitate timely 
conservation decisions, we recommend to use the regularized approach with a 
weakly-informative prior in the detection and estimation of trend with short 
and noisy time-series of abundance estimates.



Please send any questions to Matthieu: matthieu.auth...@univ-lr.fr


Cheers,

Anita


   -----------------------------------------------------------------------------
    Dr. Anita Gilles
    University of Veterinary Medicine Hannover, Foundation
    Institute for Terrestrial and Aquatic Wildlife Research (ITAW)
    Werftstr. 6 | 25761 Büsum
    Germany
    Phone: +49 (0)511-8568177
    Fax: +49 (0)511-8568181
    anita.gil...@tiho-hannover.de
    http://www.tiho-hannover.de/index.php?id=5380
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